JP2000303088A - Lubricant composition and rolling bearing using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricant composition which can prevent a rolling bearing used under severe conditions from reaching its fatigue life at an early stage, enables the life to be extended and is excellent in heat resistance by compounding a fluorine-containing base oil with a fluororesin-based thickener and an organic antimony compound or an organic molybdenum compound. SOLUTION: This composition it prepared by compounding 100 pts.wt. component comprising 70-80 wt.% fluorine-containing synthetic oil having a kinematic viscosity (40 deg.C) of 140-260 mm2/s and 30-20 wt.% fluororesin-base thickener with 2-25 pts.wt. compound selected from among antimony dithiocarbamates of formula I, antimony dithiophosphate of formula II, molybdenum dithiocarbamates of formula III and molybdenum dithiophosphates of formula IV. The composition is filled into a gap between a rolling element and an outer ring. In the formulas, R1 to R8 are each H, an alkyl or an aryl; and (m), (x) and (y) are each an arbitrary number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant composition used under severe conditions such as high temperature, high speed rotation and high load, and a rolling bearing using the same.

[0002]

2. Description of the Related Art Lubricating compositions used for lubrication around automobile engines, such as rolling bearings for alternators, have been used under severe operating conditions such as high temperature, high speed rotation and high load. It is required to exhibit sufficient lubrication performance over a long period of time without causing seizure or the like, and various improvements have been made in response to this.

[0003] However, with the rapid and rapid improvement in performance of engines in recent years, the use conditions of lubricant compositions tend to be higher temperatures, higher speeds, and higher loads than ever before. Then, it is becoming difficult to fully cope with this tendency.

[0004]

For example, the use conditions of the rolling bearing for the alternator are that the engine speed is increased and the torque is increased. In the case of a water-cooled alternator that circulates cooling water from a radiator inside a generator, which has recently begun to be partially adopted, a rolling bearing is disposed inside a thick casing. It is expected that the temperature will be unprecedented, such as above ℃.

When a conventional lubricant composition is used for a rolling bearing used under severer operating conditions than before, the rolling bearing has a theoretically estimated service life. Before the time, there is a problem that the fatigue life is reached in a very short time, and there is also a problem that the lubricant composition itself is liable to be deteriorated due to the high heat.

SUMMARY OF THE INVENTION An object of the present invention is to prevent a rolling bearing used under particularly severe conditions from having an early fatigue life, to extend the life of the rolling bearing, and to improve the heat resistance of the rolling bearing itself. An object of the present invention is to provide an excellent lubricant composition and a rolling bearing enclosing the same.

[0007]

In order to solve the above-mentioned problems, the present inventors first set the rolling bearing to reach the fatigue life in a very short time before the theoretically estimated life time as described above. The cause was examined. As a result, during the high-speed rotation, an excessive tangential force is generated between the rolling element and the rolling surface of the inner and outer rings of the rolling bearing, which causes an excessive tangential force, which leads to an early fatigue life of the rolling bearing. In order to prevent, in the lubricant composition, for example, reacting with the metal forming the rolling surface or the surface of the rolling element of the inner and outer rings, the respective surface,
It has been found that a compound capable of forming a compound film contributing to a reduction in tangential force may be added as an antiwear agent.

[0008] Then, the specific types of compounds having excellent effects as such wear inhibitors are examined, and when combined with the above compounds, the characteristics of these compounds can be maximized, and As a result of further study on a lubricating base oil capable of forming a lubricant composition excellent in heat resistance of itself and a thickener, the lubricating agent has the best lubricating performance for the use conditions of the rolling bearing, and as a result, the present invention It was completed.

That is, the lubricant composition of the present invention comprises (1) a fluorinated synthetic oil as a lubricant base oil, (2) a fluororesin thickener, and (3) an organic antimony compound and an organic molybdenum compound. And at least one compound selected from the group.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below. In the present invention, as the fluorine-based synthetic oil used as the lubricating base oil, any of various fluorine-based synthetic oils containing fluorine in the molecule thereof and having excellent heat resistance can be used. (Five):

[0011]

Embedded image

Wherein n is from 7 to 60, a homopolymer of hexafluoropropylene epoxide of a low molecular weight whose terminal is capped with fluorine, and the chain of the polymer is completely saturated. Further, a so-called perfluoroalkyl polyether (PFPE) is preferably used.
As such PFPE, there are various molecular weights using various perfluoroalkyl as a raw material, and one having a viscosity suitable for the use conditions of the lubricant composition may be selected and used.

[0013] For example, in the case of the above-mentioned lubricant composition used for a rolling bearing for a water-cooled alternator, the lubricating composition is 40%.
Kinematic viscosity at ℃ is preferably about 140~260mm ² / s. When the kinematic viscosity at 40 ° C. is less than the above range, even if a thickener described below is added in a large amount, as a lubricant for rolling bearings for the water-cooled alternator, particularly when used under high temperature conditions. The required viscosity may not be obtained. Conversely, if the kinematic viscosity at 40 ° C. exceeds the above range, the driving torque of the rolling bearing increases, the power consumption of the water-cooled alternator increases, and the grease softens due to shearing, and the rolling bearing As a result, the life of the rolling bearing may be shortened.

As the thickener, a fluororesin-based resin is used, and among them, polytetrafluoroethylene resin (PTFE) is particularly preferable. PTFE suitable for the thickener is a dispersion type or a powder type, and has a secondary particle size of 2 to 2.
The amount of the fluororesin-based thickener, such as the above-mentioned PTFE, is not particularly limited, and can be appropriately changed depending on the conditions of use of the lubricant composition. In the lubricant composition used for the rolling bearing for the water-cooled alternator, the mixing ratio of the fluorine-based synthetic oil (B) as the lubricating base oil and the fluororesin-based thickener (T) is represented by a weight ratio B / It is preferably about 70/30 to 80/20 represented by T.

If the amount of the thickener is less than the above range, the viscosity required for a lubricant may not be obtained, especially when used under rolling conditions for the above-mentioned water-cooled alternator, especially under high temperature conditions. . Conversely, if the compounding amount of the thickener exceeds the above range, the grease becomes hard and the fluidity is reduced, which may cause poor lubrication.

As described above, for example, by reacting with the metal forming the rolling surfaces of the inner and outer races of the rolling bearing and the surface of the rolling element, a compound film contributing to the reduction of the tangential force can be formed on each surface. Examples of the antiwear agent include at least one compound selected from the group consisting of organic antimony compounds and organic molybdenum compounds. Among them, the organic antimony compound includes, for example, a compound represented by the formula (1):

[0017]

Embedded image

Wherein R ¹ and R ² are the same or different and each represent a hydrogen atom, an alkyl group or an aryl group. And an antimony dithiocarbamate represented by the formula (2):

[0019]

Embedded image

[Where R^Three, R^FourAre the same or different hydrogen
Represents an atom, an alkyl group or an aryl group. ]
Antimony dithiophosphate. Up
Antimony dithiocarba represented by the general formula (1)
Specific compounds of mate include, for example, RT
-Vanderbilt Company, R.T.
nc.) (VANLUBE 73) [General formula (1)
R in¹, R ^TwoIs a compound in which is an alkyl group.
Antimony dithiophospho represented by the general formula (2)
For example, the same compounds as
Brand name "VANLUB" manufactured by Tea Vanderbilt
E 622 "[R in the general formula (2)^Three, R^FourIs an alkyl group
Certain compounds].

As the organic molybdenum compound, for example, a compound represented by the formula (3):

[0022]

Embedded image

[Wherein R ⁵ and R ⁶ are the same or different and each represent a hydrogen atom, an alkyl group or an aryl group, and m, x, y
Indicates an arbitrary number. And a molybdenum dithiocarbamate represented by the formula (4):

[0024]

Embedded image

Wherein R ⁷ and R ⁸ are the same or different and each represent a hydrogen atom, an alkyl group or an aryl group. And molybdenum dithiophosphate. Specific examples of the molybdenum dithiocarbamate represented by the general formula (3) include, for example, the same product name as “MOL” manufactured by RT Vanderbilt
YVAN A "and the specific compound of molybdenum dithiophosphate represented by the general formula (4) include, for example, the above-mentioned trade name" MOLYVAN L "manufactured by RT Vanderbilt.

These compounds can be used alone or in combination of two or more. The amount of the above-mentioned organic antimony compound or organic molybdenum compound added as an antiwear agent was 10% in total of the lubricating base oil and the thickener.
It is preferably about 2 to 25 parts by weight with respect to 0 parts by weight.

If the amount of the anti-wear agent is less than the above range, the effect of the addition of the anti-wear agent becomes insufficient, and for example, the surface of the rolling surface of the inner and outer races of the rolling bearing or the rolling element becomes insufficient. There is a possibility that a compound film having a sufficient tangential force reducing effect cannot be formed. Conversely, if it exceeds the above range, not only the further effect of addition cannot be expected, but also there is a possibility that it may be disadvantageous in terms of economic effect.

To the lubricant composition of the present invention, various conventionally known additives such as an extreme pressure agent (for example, potassium borate), an antioxidant, and an antirust agent are added in the same ratio as the conventional one. May be. The rolling bearing of the present invention is manufactured by enclosing the lubricant composition of the present invention. The type of the rolling bearing is not particularly limited, and the configuration of the present invention can be applied to various types of conventionally known rolling bearings. The amount of the lubricant composition to be filled can be appropriately changed according to the type and dimensions of the rolling bearing, but may be substantially the same as the conventional one.

For example, in the case of the above-mentioned rolling bearing for a water-cooled alternator, it is preferable that the lubricant composition is filled in an amount of about 30 to 40% of the volume of the gap between the rolling element and the outer ring without the rolling element.

[0030]

The present invention will be described below based on examples and comparative examples. In addition, each component used in each Example and Comparative Example was
It is as follows. * Lubricating base oil PFPE1: Perfluoroalkyl polyether [40
Kinematic viscosity at 160 ° C. 160 mm ² / s].

PFPE2: Perfluoroalkyl polyether [kinematic viscosity at 40 ° C. 240 mm ² / s]. PAO: poly-α-olefin [kinematic viscosity at 100 ° C. 8
mm ² / s]. ADE: alkyl diphenyl ether [kinematic viscosity at 100 ° C. 12 mm ² / s]. * Thickener PTFE: polytetrafluoroethylene resin [having a secondary particle size of 3 to 5 µm synthesized by an emulsion polymerization method].

Diurea: a reaction product of p-dodecylaniline, cyclohexylamine, and 4,4'-diphenylmethane diisocyanate (described in detail below). * Abrasion inhibitor SbDTC: antimony dithiocarbamate wherein R ¹ and R ² in the above general formula (1) are alkyl groups [trade name “VANLU” manufactured by RT Vanderbilt Co., Ltd.
BE 73 "].

MoDTC: Molybdenum dithiocarbamate of the general formula (3) [trade name "MOLYVAN A" manufactured by RT Vanderbilt Co., Ltd.] MoDTP: molybdenum dithiophosphate of the general formula (4) [trade name “MOLYVAN L” manufactured by RT Vanderbilt Co., Ltd.). * Antioxidant Alkylated diphenylamine * Rust inhibitor Sodium nitrite Examples 1-6 Among the components shown in Table 1, lubricating base oil and thickener were put in a stainless steel container and gelled by stirring at room temperature. Was.
Next, the abrasion inhibitor, antioxidant, and rust inhibitor in the amounts shown in Table 1 were added to 1000 parts by weight of the above gel, and the mixture was further stirred and homogenized using a three-roll mill. The lubricant compositions of Examples 1 to 6 were produced.

Comparative Examples 1 and 2 Lubricating compositions of Comparative Examples 1 and 2 were produced in the same manner as in Examples 1 to 6 except that no wear inhibitor was added. Comparative Examples 3 to 6 To 425 parts by weight of a lubricating base oil, 64 parts by weight of p-dodecylaniline as an amine component and 25 parts by weight of cyclohexylamine were mixed, and heated to 100 ° C. while stirring to prepare an amine solution. did. In addition, 425 parts by weight of the same lubricating base oil and 61 parts by weight of 4, as an isocyanate component,
4'-Diphenylmethane diisocyanate was mixed and heated to 100 ° C. with stirring to prepare an isocyanate solution.

While stirring the isocyanate solution, the amine solution was gradually added and reacted to form a lubricant base oil 850.
150 parts by weight of diurea were produced in parts by weight. Next, in order to uniformly disperse the generated diurea, the reaction solution was heated with stirring and heated to 150 ° C.
After holding for 5 to 40 minutes, the mixture was gradually cooled to room temperature to gel.

Then, while continuing stirring, the above gel 10
To 00 parts by weight, the abrasion inhibitor, antioxidant, and rust inhibitor in the amounts shown in Table 2 were added, and the mixture was further stirred, and then homogenized using a three-roll mill to obtain Comparative Examples 3 to 6. Was prepared. The lubricant compositions produced in the above Examples and Comparative Examples were subjected to the following tests to evaluate the characteristics.

Measurement of the penetration consistency The penetration penetration (60 W) of the lubricant composition produced in each of the examples and comparative examples was measured according to Japanese Industrial Standard JIS K 2220.
It was measured according to the method for measuring the penetration consistency described in “Grease”. Measurement of bearing life The lubricant compositions produced in each of the examples and comparative examples were each applied to a radial ball bearing with both seals (nominal number 6303ZR).
After charging 2 g in D), operation was performed for 1,000 hours under the following high-speed and high-load conditions, and the time required for peeling to occur on the raceway surface and causing damage to the bearing was measured. Note that the measurement was performed four times using four radial ball bearings for each sample.

(Operating conditions) Rotation speed: 18000 rpm Radial load: 250 kg Temperature: 90 ° C. Rated load C: 13.5 KN Heat resistance test
After operating for 0 hours, the time required for the bearing composition to break due to seizure of the lubricant composition was measured. Note that the measurement was performed four times using four radial ball bearings for each sample.

(Operating conditions) Rotation speed: 18000 rpm Radial load: 100 kg Temperature: 200 ° C. Rated load C: 13.5 KN The results obtained above are shown in Tables 1 and 2.

[0040]

[Table 1]

[0041]

[Table 2]

From the above table, it can be seen that all of the lubricant compositions of Comparative Examples 3 to 6 contain an organic antimony compound as an antiwear agent,
Although it contains an organic molybdenum compound, it has the effect of improving the life of the bearing, but it uses PAO and ADE, which are lubricating base oils other than the fluorinated synthetic oil, and increases the non-fluororesin based oil. It was found that the use of a diurea compound as an agent had insufficient heat resistance per se.

On the other hand, the lubricant compositions of Comparative Examples 1 and 2 in which a fluorine-based synthetic oil and a fluororesin-based thickener were combined were both excellent in heat resistance per se, but as organic antimony as an antiwear agent. It was found that since the compound and the organic molybdenum compound were not contained, the effect of improving the life of the bearing could not be obtained. In contrast, Example 1
It has been confirmed that all of the lubricant compositions Nos. To 6 have an effect of improving the life of the bearing and have excellent heat resistance.

[0044]

As described above in detail, according to the present invention, it is possible to prevent a rolling bearing used under particularly severe conditions from having an early fatigue life and to extend the life of the rolling bearing. At the same time, the present invention has a specific function and effect of being able to provide a lubricant composition excellent in heat resistance of itself and a rolling bearing enclosing the same.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10N 10:10 10:12 30:06 30:08 40:02 50:10 (72) Inventor Seiji Okamura 18-21 Toyosaki Building, Chaya-cho, Kita-ku, Osaka Japan Grease Co., Ltd. (72) Inventor Hiroki Iwamatsu 18-21 Toyosaki Building, Chaya-cho, Kita-ku, Osaka City Japan Grease Co., Ltd. F-term (reference) 4H104 BD06A BG10C BH07C CD02B CD04A FA05 FA06 LA03 LA04 LA20 PA01 QA18

Claims (6)

[Claims] (1) at least one selected from the group consisting of (1) a fluorine-based synthetic oil as a lubricating base oil, (2) a fluororesin-based thickener, and (3) an organic antimony compound and an organic molybdenum compound. A lubricant composition comprising: 2. The lubricant composition according to claim 1, wherein the fluorinated synthetic oil is a perfluoroalkyl polyether. 3. The lubricant composition according to claim 1, wherein the fluororesin thickener is a polytetrafluoroethylene resin. 4. An organic antimony compound represented by the formula (1): [Wherein R ¹ and R ² are the same or different and each represent a hydrogen atom, an alkyl group or an aryl group. And an antimony dithiocarbamate represented by the formula (2): [Wherein R ³ and R ⁴ are the same or different and each represent a hydrogen atom, an alkyl group or an aryl group. The lubricant composition according to claim 1, which is at least one of antimony dithiophosphates represented by the following formula: 5. The organic molybdenum compound represented by the formula (3): [In the formula, R ⁵ and R ⁶ are the same or different and each represent a hydrogen atom, an alkyl group or an aryl group, and m, x, and y each represent an arbitrary number. And a molybdenum dithiocarbamate represented by the formula (4): Wherein R ⁷ and R ⁸ are the same or different and each represent a hydrogen atom, an alkyl group or an aryl group. The lubricant composition according to claim 1, which is at least one of molybdenum dithiophosphates represented by the formula: 6. A rolling bearing comprising the lubricant composition according to claim 1.